The present invention relates to a control circuit for a liquid fuel combustion apparatus utilizing an electromagnetic pump for fuel feeding, wherein a thermo-sensitive element detects room temperature to control fuel feeding to a burner thereby automatically maintaining a desired room temperature, thus economizing fuel and preventing air pollution in the room resulting from incomplete combustion.
Automatic room temperature control in conventional kerosene combustion apparatus has been conducted by (1) repeated ignition and extinguishing of the burner or (2) repeated strong and weak combustion.
In the above-mentioned method (1), the combustion is continued at a pre-determined rate until a preselected room temperature is reached. The burner is extinguished when the room temperature exceeds the preselected value. Combustion is started again as the room temperature becomes lower than said predetermined value. Consequently, the burning period of the burner becomes longer as the difference between the room temperature and the preselected temperature is larger or as the room area is larger, and vice versa.
This method is defective in that the burner tends to generate soot or unburnt gas due to unstable combustion soon after burner ignition. This method also tends to release unburnt gas after the burner is extinguished. Furthermore, repeated combustion and extinguishing causes significant temperature fluctuation in the vicinity of the burner, causing discomfort to the user.
The above-mentioned method (2) is associated with discomfort resulting from temperature fluctuation, although the formation of soot or unburnt gas can be prevented in this case.
In addition, the repeated ignition and extinguishing or repeated switching between strong and weak combustion in the methods (1) or (2) leads to an accelerated wear of the equipment, reducing the service life thereof.
Accordingly, it is an object of the present invention to provide a control circuit for a combustion apparatus which comfortably regulates room temperature.
Another object of the present invention is to provide a control circuit for a combustion apparatus which comfortably regulates room temperature without generation of soot or unburnt gas.
A still further object of the present invention is to provide a control circuit for a combustion apparatus which comfortably regulates room temperature without requiring a relatively long period for reaching a target temperature.